Storm drains, commonly located in roadways, parking lots or beside sidewalks, are ordinarily covered by a simple metal grating that supports vehicular and foot traffic at ground level, while serving the dual purposes of preventing large objects and debris from entering the drain while also providing a barrier for pedestrians and animals. Such a grating does not provide a substantial obstacle to the entry of any but the largest of debris into the drain; as a result the drain may become clogged when large volumes of debris are swept through the grating and into the drain by the liquid medium. Furthermore, the grating itself may become clogged when large materials such as fibrous materials amass and cover the opening.
Thus, where there is a potential for large amounts of sediment or debris being washed into a storm drain, such as near a construction or roadway repair site, there exists a need for additional protection and filtration to reduce the amount of debris reaching the grating any being introduced into the storm drain itself. This need is augmented by the fact that runoff water, which may contain undesirable or hazardous materials, is often directly channeled to the ocean or other public bodies of water. As a matter of general public safety and in view of environmental laws and regulation prohibiting the contamination of such resources, water entering storm drains must be free of large amounts of debris and pollutants.
Products have been developed to prevent sediment or other materials from flowing into storm drains in such situations. U.S. Pat. No. 7,481,921, granted to Kent on Jan. 27, 2009, discloses a cleanable and reusable fibrous mat adapted to filter water that is placed over the top of a preexisting grating on a storm drain. Unfortunately, storm drains are subject to variable flow rates, with very high rates being common. Although the Kent apparatus succeeds in preventing the passage of sediment and small debris that would otherwise bypass the grating, such a fibrous mat would need to be continuously cleaned and would quickly clog in high flow situations or if left untended for any significant period of time. Moreover, the Kent apparatus provides no method of filtering liquid contaminants, such as motor oil, that may commonly find their way to storm drains.
A device made by Ertec Environmental Systems, termed the GR8 Guard™, provides a flat filter device comprising an apertured polymeric inlet (threshold) member, an apertured polymeric outflow member, and a filter member secured to one or both of the threshold member and the outflow member. The perimeter of the filter sheet (i.e., about 4″ inward from the perimeter of the device) is surrounded by a folded-over piece of material (such as a geotextile material) to act as a dam or barrier to prevent sediment flow from reaching the filter. However, this perimeter “fence” is not sturdy and if contacted with a strong flow of sediment-containing water, or if the filter device is run over by a motor vehicle, the dam will tend to fold down thereby becoming inoperable and defeating a major purpose of the barrier.
As such, there remains a need for a sediment control device containing a dam or berm that is sturdy enough to withstand high flow rates and vehicle traffic without buckling or collapsing.